Nutrition per serving may change if servings are adjusted.
1½ teaspoons unflavored gelatin
1 tablespoon water
3 cups low-fat milk, divided
3 large egg yolks
1 14-ounce can nonfat sweetened condensed milk
¼ cup unsweetened cocoa powder
2 ounces chopped unsweetened chocolate
¾ cup chopped chocolate sandwich (or wafer) cookies
¼ cup chopped toasted walnuts, (see Tip)
Sprinkle gelatin over water in a small bowl; let stand, stirring once or twice, while you make the base for the ice cream.
Pour 1½ cups milk into a large saucepan. Add cocoa and chocolate to the milk.
Heat the milk mixture over medium heat until steaming. Whisk egg yolks and condensed milk in a medium bowl. Gradually pour in the hot milk, whisking until blended. Return the mixture to the pan and cook over medium heat, stirring with a wooden spoon, until the back of the spoon is lightly coated, 3 to 5 minutes. Do not bring to a boil or the custard will curdle.
Strain the custard through a fine-mesh sieve into a clean large bowl. Add the softened gelatin and whisk until melted. Whisk in the remaining 1½ cups milk. Cover and refrigerate until chilled, at least 2 hours.
Whisk the ice cream mixture and pour into the canister of an ice cream maker. Freeze according to manufacturer's directions. During the last 5 minutes of freezing, add chopped cookies and walnuts to the ice cream maker. If necessary, place the ice cream in the freezer to firm up before serving.
Make Ahead Tip: Store in an airtight container in the freezer for up to 1 week.
Equipment: Ice cream maker
Tip: Toasting chopped nuts: Cook in a small dry skillet over medium-low heat, stirring constantly, until fragrant and lightly browned, 2 to 4 minutes. Cool toasted nuts completely before adding them to the ice cream maker.